Coating apparatus

ABSTRACT

A method and apparatus for the accurate coating of liquids, particularly adhesives, onto selected areas of the surface of an article. The article is positioned above the surface of the liquid in correspondence with a tool below the liquid surface. The tool corresponds in shape to the selected areas of the article. Raising the tool without breaking the surface of the liquid causes the liquid above it to rise and contact the article in the selected areas only, of which the following is a specification.

United States Patent [191 McGlashen COATING APPARATUS [75] Inventor:James N. McGlashen, Winstanley,

England [73] Assignee: Dunlap Holdings Limited, London,

England [22] Filed: Dec. 2, 1971 [21] Appl. No.: 204,262

[30] Foreign Application Priority Data Dec. 16, 1970 Great Britain59827/70 [52] U.S. Cl 118/421, 228/1, 228/37 [51] Int. Cl. B05C 3/20[58] Field of Search 118/421, 300, 429; 228/1, 228/37; 117/113, 116, 114R, 114 A, 114 B, 114 C; 134/1 NO; 68/1 NO [56] References Cited UNITEDSTATES PATENTS 1,258,071 3/1918 Winter 118/421 X 1,746,416 2/1930 Butler118/421 UX 1,988,955 l/l935 Nehmert 118/421 X 2,159,091 5/1939 Kopitke118/421 [11] 3,823,687 [4 July 16,1974

2,260,282 .10/1941 Grint 118/421 X 2,578,627 12/1951 Brent 118/4212,771,049 11/1956 Fish 118/421 UX 3,084,650 4/1963 Johns 118/429 X3,383,906 5/1968 Gillet 118/421 X 3,618,566 11/1971 Walker et a1.118/429 3,675,622 7/1972 Griffin..... 118/421 3,691,988 9/1972Clarke..... 118/421 X Primary Examiner-Morris Kaplan Attorney, Agent, orFirm-Stevens, Davis, Miller &

Mosher A 57 ABSTRACT A method and apparatus for the accurate coating ofliquids, particularly adhesives, onto selected areas of the surface ofan article. The article is positioned above the surface of the liquid incorrespondence with a tool below the liquid surface. The toolcorresponds in shape to the selected areas of the article. Raising thetool without breaking the surface of the liquid causes the liquid aboveit to rise and contact the article in the selected areas only, of whichthe following is a specification.

7 Claims, 12 Drawing Figures cam-ales? PATENTEI] JUL I 6 I974 sum 1 or 6PATENTEDJUL 1 6|974 L687 SHEET 2 OF 6 sum 3 or 6 PATENTEU JUL 1 6 m4PATENTED JUL 1 6 I974 SHEU 8.0? 6

PATENTEU JUL 1 81974 sum 6 or 6 '6 COATING APPARATUS This inventionrelates to an apparatus for applying a liquid coating to a surface. Itis particularly concerned with the application of adhesive in liquidform, for example rubber solutions, but is not limited thereto.

In one aspect therefore the invention provides an apparatus for applyingliquid to selected areas of an article, in which the article ispositioned above the surface of the liquid so that it is incorrespondence with a tool positioned beneath the surface of the liquid,the tool being shaped to correspond with the selected areas of thearticle, and the tool is raised so that it does not break the surface ofthe liquid but causes the liquid above the tool to rise, therebybringing the liquid into contact with the selected areas of the article.

The invention also provides an apparatus for applying liquid to selectedareas of an article which comprises a bath to contain the liquid, a toolpositioned to lie within the bath beneath the surface of the liquid,means to position the article above the bath in correspondence with thetool and means to raise the tool towards the article without breakingthe surface of the liquid, the tool being shaped to correspond with these lected areas of the article.

The means to position the article above the bath may conveniently be,for example, a pair of guide rails running across and above the bath.The article can be carried in a suitably shaped jig, the jig having apair of arms to locate on and run along the guide rails.

As indicated above, the invention is particularly concerned with theapplication of adhesives. It is not, however, limited thereto and canequally well be applied to a diversity of liquids, for example theprinting of patterns with inks and other liquid printing media and tothe application of such liquids as molten solder. However, forconvenience the invention will be more specifically described withreference to the application of adhesives.

Many articles are made by adhering together their component pieces andthis is frequently done by means of glues, rubber solutions, solventsand like liquid adhesives. The application of liquid adhesives whetherdone automatically, semi-automatically or manually is apt to be aninexact technique resulting in either a deficiency of adhesive in someareas or a surplus'of unwanted adhesive in other areas or both. In manycases the application of an excess of adhesive in an area to be coated,or of adhesive in areas not desired to be coated, can be veryinconvenient-and may well hinder the subsequent steps in the productionof the article in question. A deficiency of adhesive in certain areasmay also, of course, result in unsatisfactory bonding in the product.

The present invention mitigates this problem in that it allows acontrolled application to be achieved with greatly reduced risk of asurplus or deficiency of adhesive, or other liquid, being applied in anyarea.

In order to obtain the best results it is preferable to keep the liquidat a constant level in the bath. This can be achieved by any convenientmeans, for example recirculating means and a weir. The bath canconveniently be provided with a weir at each end and pumping means toreturn excess liquid carried over the weir back into the bath. Bykeeping the level of the liquid in the bath constant it is possible tokeep the travel of the tool constant and similarly to keep the requiredposition of the article above the bath in the actual coating positionconstant. Thus the apparatus can be set to accurate working limits andcan be run without requiring the continuous adjustments which would benecessary if the level of the liquid was allowed to fall. Recirculatingof the liquid has an added advantage where a liquid such as an adhesiveis used in that it prevents skinning over of the surface of the liquid.

The height by which the liquid can be raised by the tool depends on thespeed of raising the tool, the viscosity of the liquid and the area ofthe tool. The heights are of course relatively small. For example, whenusing a latex-based adhesive having a viscosity of to seconds whenmeasured by the Ford Viscosity Cup No. 4, a suitable height to positionthe article to be coated above thesurface of theliquid is about oneeighth of an inch. The method has been found to work satisfactorilyusing water but in general, as the viscosity of the liquid increases,the effect of the invention is more marked.

In a convenient embodiment of the invention the tool has a rest positionjust below the surface of the liquid, for example one eighth of aninchbelow the surface. When the article to be coated is in position abovethe tool the latter is depressed and then returned or allowed to returnto its rest position. This causes the liquid immediately above the toolto rise momentarily above the general level of the liquid surface andthereby to contact and coat the article as desired. This movement of thetool can be achieved for example by means of a lever and springarrangement whereby the tool is depressed by means of the lever and isthen returned to its rest position by action of the spring.Alternatively, the tool may have a rest position somewhat further belowthe surface of the liquid and it may then be raised to a position justbelow the surface of the liquid and then returned to its rest-position.At its highest point the tool will have raised the liquid immediatelyabove it sufficiently for the liquid to contact the article to becoated. A similar lever and spring system can be used to achieve thismovement of the tool.

As indicated-above, the height of the article above the liquid, theposition and the speed of movement of the tool will vary with the typeof liquid used, but. it is a reasonably straightforward matter todetermine the optimum conditions for any particular system. Similarlythe optimum width of tool to coat any particular article will vary withthe viscosity of the liquid. In general, the less viscous the liquid thewider the tool must be, but again optimum conditions can be readilydetermined for any system.

The invention is particularly useful in the application of adhesive tothe edges of hemispherical half-shells which are then to be joinedtogether to form hollow spheres. For example, in the manufacture of thehollow rubber cores of tennis balls andsquash balls the cores areconventionally made by first forming two partly cured rubberhalf-shells, dipping the rims of the halfshells into-a suitableadhesive, sticking the two halves together and then completing the curein a mould. The adhesive application stage is messy andprone toinaccuracy. As shown below with reference to FIG. 1, the adhesive isliable to coat part of the outer walls of the core halves. This makessubsequent-handling more difficult in addition to being wasteful.

Accordingly, in a further aspect the invention provides an apparatus forapplying adhesive to the rim of a hemispherical half-shell, in which thehalf-shell is positioned pole uppermost above a bath of the adhesive incorrespondence with an annulus positioned beneath the surface of theadhesive, the annulus being shaped to correspond with the rim of thehalf-shell, the annulus is raised so that it does not break through thesurface of the adhesive but causes the adhesive above the annulus torise, thereby bringing the adhesive into contact with the rim of thehalf-shell.

The invention also provides an apparatus for making a hollow rubber corefor a tennis ball, squash ball or the like, in which the core is firstformed as two partially cured hemispherical half-shells, the rim of eachhalfshell is coated with adhesive by the aforesaid method,

the two halves are then brought together and the cure is completed.

In coating the rim of a half-shell it is not essential to use 'anannulus as the tool; for example, a disc can be used. Where a disc isused, the liquid may coat partway up the inside wall of the half-shellbut the outside wall can still be left liquid-free. Thus if it is notimportant in any particular article that the insidebe free of liquid, adisc can equallyv well be used instead of an annulus.

When coating the rim of an article such as a hemispherical half-shell,there is'a tendency'for a bubble of the liquid to form across the mouthof the half-shell. This bubble will eventually burst and may leave asplash of liquid on the inside wall. Again, for many articles this maybe unimportant but, if it is desired to keep the inside wallliquid-free, the following technique can be used. This entailsintroducing a vent pipe from the atmosphere into the air volume enclosedby the article being coated and the liquid. Bubble formation across themouth of the article is thereby prevented. This venting technique,fwillnot, of course, be necessary where open-ended articles, for exampletubes, are being coated since such articles are self-vented.

One further useful advantage of the method utilizing the apparatus ofthe invention is that, as the tool never breaks through the surface ofthe liquid in normal operation, there will be no build-up ofoxidized,.skinned or otherwise degradedliquid on the tool.

Yet another useful advantage of the method utilizing the apparatus ofthe inventionresults from the clean, accurate coating which is achieved.As indicated above, it is now possible to mechanically coat withadhesive only those areas of the component parts of an article which aredesired to be stuck together. This enables an improved means of joiningtwo rim-coated half-shells to be utilized.

Basically this improved joining means comprises fitting the rim-coatedhalf-shells into opposite ends of a tube so that their adhesive-coatedrims are facing, the two shells are then pressed together in the tubeuntil their rims are pressed into abutment and are thereby joined. Thistechnique is a yet further aspect of the present invention. It will beappreciated that this joining technique is only practical for continuousproduction if the outer walls of the half-shells are substantially freefrom adhesive.

Various embodiments of the invention are illustrated in the accompanyingdrawings in which:

FIG. 1 is a sectional representation of a conventional dippingtechnique;

FIG. 2 is a similar representation of the technique of the presentinvention;

FIG. 3 is a similar representation showing the effect of introducing avent pipe;

FIG. 4 is a perspective view with parts cutaway of a typical coatingapparatus showing a bath in broken lines containing a liquid, a leverand spring mechanism to lower and raise the annulus and means toposition the article above the bath;

FIG. 5 is a sectional view on the line V-V of FIG. 4 showing an articleat the moment of being coated; and

FIGS. 6 to 12 are diagrammatic representations .of the various stages inthe improved joining'technique provided by the invention.

In FIG. 1 ahemisphere is shown having a liquid 22, e.g., adhesive,applied to its rim 21 by a conventional dipping technique. Rim 21 isdipped into the surface 23 of the liquid causing an'annular depression24 to be'formed. .T he rim isthen removed from contact with the liquid.The surfacev tension'of the liquid is broken in the areas of depression24 and the liquid tends to flow partway up the walls 25 of thehemisphere as indicated. i

In FIG. 2, the rim21 of hemisphere 20 is coated with liquid 22' usingthe method of the present invention. An annulus '26 is positionedbeneath the surface '23 of the liquid, the annulus being of meandiameter equal to the mean diameter of the rim ofthe hemisphere. (Bymean diameter is meant the average external and internal diameters). Thehemisphere is positioned with its rim 21 just above the surface of theliquid so that it is in correspondence with the annulus. The annulusisthen raised from its initial position shown in broken lines to theposition shown just below the surface of the liquid. This causes theliquid 27 immediately above the annulus to rise and contact the rim 21.The annulus is then returned down to its initial position and the raisedliquid hemisphere 20 with liquid 22. A ventv pipe 28 is'introduced fromthe atmosphere through liquid 22 into the air space 31 inside thehemisphere. When the annulus 22 has been raised to bring the liquid intocontact with rim 21, it is found that, in the absence of avent pipe, abubble 29 may tend to form across the mouth of the hemisphere in theposition shown in broken lines. This bubble formation is undesirablesince, when the bubble is broken, liquid will splash the inside walls ofthe hemisphere, and for certain applications this' may not be wanted.However, the presence of vent pipe 28 prevents the formation of bubble29 and, if any bubble formation takes place at all, it will be betweenthe rim 21 and the general surface 23 -of the liquid. Such a bubble isshown M30. The bursting of this bubble is less likely to depositundesirable liquid splashes on the article being coated. v

FIG. 4 shows an apparatus of the invention, adapted to coat the rim of ahollow hemisphere withliquid, e.g.,

adhesive and FIG.--5 shows a sectional view on the line V-V of F 16.4.The apparatus comprises a rectangular bath 40 which contains the liquid41. Inside the bath is positioned an annulus 42 of size and shapecorresponding to the article to be coated, i.e., the rim of hollowhemisphere 43. The annulus 42 has two positions in the bath, betweenwhich it can be moved by a lever and spring arrangement. The annulus isconnected via two U-shaped arms 44 to a lever 45 outside the bath. Thelever is pivoted at 46 and its movement up or down is controlled by twosprings 47 on opposite sides of the bath.

The means to position the hemisphere over the liquid in the bathcomprises two L-shaped guide rails 48 running across the top of thebath. The hemisphere 43 is fitted into a jig 49, this jig having a pairof arms 50. These arms locate the jig on the guide rails and enable itto be slid across the top of the bath above the surface of the liquid.

In operation, therefore, a hemisphere 43 is fitted into jig 49 and thearms 50 of the jig are located on the guide rails 48 and slid to acentral position above the bath so that the hemisphere is directly aboveannulus 42. Liquid to be applied to the rim of the hemisphere ismaintained in the bath at a level so that the annulus in its restposition is just submerged. The annulus is depressed by pressing lever45 so that springs 47 are compressed. Lever 45 is then released, theannulus then being returned upwards to its rest position by the returnaction of the springs. This upward movement of the annulus causes theliquid immediately above it to rise briefly above the general liquidsurface, level and thereby contact and coat the hemisphere all aroundits llm.

Clearly many different forms of lever arrangement can be used toachievethe same effect and the annulus can equally well be moved upwardsfrom a rest position instead of downwards. Moreover, it will be apparentthat the apparatus can be modified so that a number of hemispheres, orother articles, can be coated simultaneously.

The improved means of joining two rim-coated hemispherical half-shellsthat is afforded by the present invention is illustrated instage-by-stage sequence in FIGS. 6 to 12.

A cylindrical joining tube 60 is employed, this having an internalannular groove 61 running around theinner wall 62 of the tube, thisgroove being located about half-way down the length of the tube. Twoplungers 63 and 64 areemployed, one being positioned opposite each openend of the tube and each plunger being slidable towards and away fromthe tube. The end 65 of each plunger facing the tube is of arcuate formcorresponding to a portion of the hemispheres to be joined. Theapparatus also comprises a frame 66 having a centrally disposed circularaperture (not shown), this aperture being ofdiameter a little less thanthe diameter of the hemispheres to be joined. The joining tube is alsoof internal diameter slightly less than that of the hemispheres but theinner wall of the tube is cut-away at each end to provide an angledlead-in portion 67 to facilitate entry of the hemisphere into the tube-In operation a first hemisphere 68, which has previously beenadhesively-coated around its rim 69 by the method of the invention, isfitted into carryingframe 66. The carrying frame is positioned betweenplunger- 63 and the tube as shown in FIG. 7, so that the pole v of thehemisphere faces end of plunger 63.-Plunger 63 is then moved towardstube 60; arcuate end 65 of the plunger contacts the surface of thehemisphere 68 and pushes the hemisphere in its frame up to theopen endof tube 60. Frame 66 then abuts on the end of tube 60 as shown in FIG.,7. The plunger 63 then pushes the hemisphere out of its frame andinside the tube until the hemisphere outer wall adjacent its rim locatesin groove 61 (FIG. 8).

Plunger 63 and frame 66 are then moved away from tube 60 back to theirstarting positions. The joining tube is then rotated through 180 so thatits other open end now faces plunger 63. FIG. 9 shows this rotationtaking place.

A second rim-coated hemisphere 70 is then fitted into frame 66 and ispushed into the tube 60 in the same manner as was hemisphere 68. Plunger64 is moved into contact with hemisphere 68 as or before hemisphere 70is pushed into the tube so that hemisphere 68 will not be dislodged whenit is contacted by hemisphere 70. FIG. 10 shows the position wherehemisphere 70 is just about to'enter the tube. If desired thishemisphere may contain gas-generating chemicals 71 so that the twohemispheres, when joined together, can be pressurized by heating toeffect the gas-forming reaction. (This effect is very useful if a tennisball core is being formed).

The actual joining together of the hemispheres is shown in FIG. 11 wherehemisphere 70 has been pushed up to groove 61 and is pressed intorim-contact with hemisphere 68. Thus the two hemispheres are joinedunder pressure at their adhesive-coated rims to form a hollow sphere 72.

FIG. 12 shows the start of the final stage, i.e., ejection of the joinedhemispheres, e.g., tennis ball core 72, from tube 60. Plunger 63 iswithdrawn and plunger 64 pushes core 72 first into a push fit in frame66 and then out of the tube completely.

It will be appreciated that this general joining technique may be variedin a number of ways. For example, instead of rotating tube 60 throughone hemisphere couldbepushed into the tube from each end, i.e., onehemisphere by plunger 63 at one end and the other hemisphere at theother end by plunger 64.

In an alternative method of making a pressurized hollow article, gasunder pressure can be introduced between. the two half-shells beforethey are joined together. Thus, for example, gas under pressure may beintroduced between thetwo half-shells just prior to their joining, thegas entering through a suitable duct in the joining tube.

The improved method of liquid application provided by the inventionenables the mass-production of articles such as tennis or squash ballcores to be more conveniently mechanised. For example a continuousproduction line can be adapted to handle the continuous solutioning andassembly of a large number of halfshells. Thus, the half-shells can beloaded into carrying slats which take, for example, ten, twelve or morehalfshells at a time. The loaded slats are then fed in turn to thesolutioning bath where the half-shells are positioned rim downwardsabove a corresponding row of annuli beneath the surface of the adhesive.Thus the rims of the half-shells of each slat can be solutionedsimultaneously and the half-shells can then be passed down the line toreceive the further necessary treatments including the finalsimultaneous assembly stage of a number of spheres.

Having now described my invention what I claim is: surface in the bath,substantially only said higher level liquid surface coming in 1. Anapparatus for applying liquid to selected areas of an article, whichcomprises a bath to contain said liquid, a tool positioned to lie withinsaid bath beneath the surface of said liquid, means to position saidarticle above said bath in correspondence with said tool and means toraise said tool towards said article without breaking the surface of theliquid, said tool locally raising the liquid surface above the tool to ahigher level than the remainder of the liquid surface coming in contactwith said article, said tool being shaped to correspond with saidselected areas of the article.

2. An apparatus according to claim 1, in which said bath contains a weirand pumping means are provided to re-circulate into the bath excessliquid which runs over said weir.

3. An apparatus according to claim 1, in which said tool is an annulus.

4. An apparatus according to claim 1, in which the means to raise saidtool comprise a lever and spring arrangement whereby the tool is firstdepressed from its rest position by means of said lever and is thenraised back to its rest position by action of said spring.

5. An apparatus according to claim 1, in which a vent pipe is providedso that the air volume between said article to which the liquid isapplied and the surface of the liquid, when liquid and article are incontact, is

vented.

6. An apparatus according to claim 1, in which said means to positionthe article above the bath comprise a pair of rails running above thebath and a jig to contain the article, said jig having a pair of arms tolocate on and run along said rails.

7. An apparatus for applying liquid to selected areas of an article,which comprises a bath to contain said liquid, a tool positioned to liewithin said bath beneath the surface of said liquid, said tool being anannulus, means to position said article above said bath incorrespondence with said tool, means to raise said tool towards saidarticle without breaking the surface of the liquid, said tool beingshaped to correspond with said selected areas of the article, saidarticle and said liquid forming a hollow closed chamber when said toolis raised, and vent means extending through said annulus and into saidclosed chamber for venting the air from said closed chamber when theliquid raised by the annulus and the article are in contact.

UNITED STATES PATENT omen CERTIFICATE OF CQRRECTEON Patent No. 3,823,687Dated July 16, 1974 Inventor(s) James N. McGlashen It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

On the title page, 'Dunlap should read --Dunlop.

In the Abstract, line 1, "A method and should read -An--.

, In column 6', lines 64-65, "surface in the bath, substantially onlysaid higher level liquid surface coming in" should be deleted.

In column 7, line 7, between "surface" and "coming" the following shouldbe inserted: T

--in the bath, substantially only said higher level liquid surface--.

Signed and sealed this 22nd day of October 1974.

(SEAL) Attest: McCOY M. GIBSON JR, C. MARSHALL DANN Attesting OfficerCommissioner of Patents FORM po'wso (169) uscoMM-oc 60376-P69 U.S.GOVERNMENT PRINTING OFFICE: I989 0-366-884,

1. An apparatus for applying liquid to selected areas of an article,which comprises a bath to contain said liquid, a tool positioned to liewithin said bath beneath the surface of said liquid, means to positionsaid article above said bath in correspondence with said tool and meansto raise said tool towards said article without breaking the surface ofthe liquid, said tool locally raising the liquid surface above the toolto a higher level than the remainder of the liquid surface coming incontact with said article, said tool being shaped to correspond withsaid selected areas of the article.
 2. An apparatus according to claim1, in which said bath contains a weir and pumping means are provided tore-circulate into the bath excess liquid which runs over said weir. 3.An apparatus according to claim 1, in which said tool is an annulus. 4.An apparatus according to claim 1, in which the means to raise said toolcomprise a lever and spring arrangement whereby the tool is firstdepressed from its rest position by means of said lever and is thenraised back to its rest position by action of said spring.
 5. Anapparatus according to claim 1, in which a vent pipe is provided so thatthe air volume between said article to which the liquid is applied andthe surface of the liquid, when liquid and article are in contact, isvented.
 6. An apparatus according to claim 1, in which said means toposition the article above the bath comprise a pair of rails runningabove the bath and a jig to contain the article, said jig having a pairof arms to locate on and run along said rails.
 7. An apparatus forapplying liquid to selected areas of an article, which comprises a bathto contain said liquid, a tool positioned to lie within said bathbeneath the surface of said liquid, said tool being an annulus, means toposition said article above said bath in correspondence with said tool,means to raise said tool towards said aRticle without breaking thesurface of the liquid, said tool being shaped to correspond with saidselected areas of the article, said article and said liquid forming ahollow closed chamber when said tool is raised, and vent means extendingthrough said annulus and into said closed chamber for venting the airfrom said closed chamber when the liquid raised by the annulus and thearticle are in contact.